I don't have any experience with African honey bees and mites, but in the absence of a response from someone who does: Varroa has a lower rate of reproduction in races (such as the African types) which have a shorter capped brood period (number of days between when the bee larval cell is capped, and when the adult emerges). In South America, there have also been reports of higher than typical non-reproducing varroa (non-viable eggs) which might be related to the climate or to the host bee. My impression (perhaps one of the contributors from S America could comment) is that varroa in S America is widespread but does not result in colony collapse, as it does in temperate areas. Some of that "resistance" may change in the North American environment. Based on their shorter lives, African honey bee might also tend to have resistance to tracheal mites (although I don't remember any research to confirm this), resulting in a lower mite reproduction similar to what occurs with European races in a strong honeyflow (short-lived bees don't provide an environment for tracheal mites to reproduce very well). As Africanized bees reach their temperate limit, however, they may get longer lives (more time in the hive waiting for the weather to improve) and this effect would decrease. Regarding the resistence mechanisms of bees to tracheal mites, the spiracle-fringe hair hypothesis was not supported by experiments many years ago. There is more recent evidence of a host age perception (by mites) based on chemical differences of newly-emerged bees, a likely resistence mechanism. There may be others, but whatever, it looks like the potential for tracheal mite resistance is not too deeply buried even in North American bees. Kerry Clark, Apiculture Specialist B.C. Ministry of Agriculture 1201 103 Ave Dawson Creek B.C. V1G 4J2 CANADA Tel (604) 784-2225 fax (604) 784-2299 INTERNET [log in to unmask]